Example: I currently pay for the Premium tier at $19.99/month where I share it with 4 other people - each of us get a profile. Price comes out to $3.99/person/month.
But, Premium tier can only add 2 additional households. 3 of us can stay on the account and 2 people are out.
Now with 3 total people on the original account, the price comes out to $19.99 + $7.99+ $7.99 / 3 = $11.99/person/month.
Now for the 2 who were kicked off - To share you have to be at least at the Standard tier for $15.49 + $7.99 / 2 = $11.74/person/month.
That ends up more expensive per-person than getting your own ad-tier ($6.99/month) or Basic tier account ($9.99/month).
Unless you care about 4K content, Netflix has incentivized each person signing up for a total net gain of 4 accounts.
And all that said, the new subscription count isn't reflecting how many people are quitting. You could have 100 accounts cancelling for every 5 signing up and it wouldn't be reflected in the data they're giving us.